The members of the Children's Cancer Study Group, using mutually agreed upon protocols, evaluate and treat children with the leukemias and with a variety of malignancies. The primary aims of such protocol studies are to carefully study the disease processes, to evaluate therapeutic regimens and to devise optimal treatment for such children in order to increase survival time and the cure rate. In addition, ancillary information regarding supportive care, toxicity, complications and survival data is gathered and evaluated.